Fix KitKat SD Card Write Restriction

This is a way of repairing permissions to write to the SD card android kitkat including Samsung S5
Just to root device
- Make sure that you have root access
- Use the file manager [Explorer]
root enabled and enter /system/etc/permissions/
- Edit platform.xml, search "WRITE_EXTERNAL_STORAGE" and add <group gid="media_rw"/>
- Save and restart
Now you can write on your external SD card again